Organizations and individuals may use virtual private network (VPNs) to communicate securely over public networks. For example, an employee may use a virtual private network to communicate securely over the Internet with a computer at the office. The use of a VPN helps to guarantee that others on the public network cannot intercept, read, or reuse communications sent on the VPN.
In general, a remote client device establishes a VPN connection with a gateway device over a public network. The gateway device may include a firewall module to prevent unauthorized network packets from the public network from reaching a private network. Furthermore, the gateway device may include various security technologies, such a Secure Sockets Layer (SSL), to ensure that communications between the client device and the gateway device are secure. After the client device establishes a VPN connection with the gateway device, the gateway device may allow network packets from the client device to pass through the gateway device a server device on a private network, and vice versa. In this way, the client device may securely interact with the server device.
Some gateway devices routinely prevent network packets that do not conform to a specific protocol from passing through the gateway device. For example, a gateway device may block all network packets that do not conform to the Hypertext Transfer Protocol security (https) protocol. In such a situation, a client device cannot send a network packet through the gateway device when the network packet conforms to another protocol, such a Server Message Block (SMB). This can cause problems for certain applications that, by default, use the other protocol.